1. Technical Field of the Invention
This invention relates to radio telecommunication systems and, more particularly, to a system and method of estimating radio channel bit error rate in a digital radio telecommunications network.
2. Description of Related Art
In digital radio telecommunications networks, the quality of the transmitted signal is often expressed in terms of how many of the received bits are corrupted, leading to the expression Bit Error Rate (BER). The BER indicates how many of the total number of bits are wrongly detected.
With the introduction of data services in radio telecommunications networks, systems that provide two grades of service are being developed. A high grade of service utilizes high level modulation to provide higher service quality for data or improved voice services. A lower grade of service utilizes low level modulation to provide service quality which is adequate for traditional voice applications. A system and method of switching between one grade of service and the other is needed. Such a system must identify which level of service is being provided, assess the adequacy of the provided service, and if the service is not adequate, perform a switch between the two. In order to accomplish these objectives, a more accurate method of determining the BER is needed.
Although there are no known prior art teachings of a solution to the aforementioned deficiency and shortcoming such as that disclosed herein, U.K. Patent Application Number GB 2,232,854 A (GEC-Marconi), U.S. Pat. No. 5,418,789 (Gersbach), and U.S. Pat. No. 5,406,562 (Roney) discuss subject matter that bears some relation to matters discussed herein. The GEC-Marconi patent discloses a method of assessing the quality of a data channel based on the processing of soft decision demodulation information. The BER may be determined more quickly because sampling time is reduced due to the use of soft decisions within a known band of levels rather than hard decisions which require longer sampling time. The GEC-Marconi patent, however, does not teach or suggest a system or method of determining the BER with such accuracy and reliability that it can be used to determine when a radio telecommunications network should switch from a low grade of service to a high grade of service.
The Gersbach patent discloses a system and method for rapidly estimating the bit error rate of a data signal which has been reconstructed from a received data signal. A bit error rate calculator is integrated with a nearly instantaneous bit error rate estimator which utilizes timing and amplitude degradation information. The Gersbach patent, however, does not teach or suggest a system or method of determining the BER with such accuracy and reliability that it can be used to determine when a radio telecommunications network should switch from a low grade of service to a high grade of service.
The Roney patent discloses a BER estimation process which receives encoded data over a channel, decodes the data, and estimates the number of errors induced by the channel. Roney discloses a method of estimating the BER on a Fast Associated Control Channel (FACCH) as well as the BER on the user channel. The two BER estimates are compared, and the difference is utilized to determine whether the received data is convolutionally encoded user information or a FACCH message. The Roney patent, however, does not teach or suggest a system or method of determining when a radio telecommunications network should switch between one grade of service and another based upon a highly accurate and reliable estimate of the BER.
Review of each of the foregoing references reveals no disclosure or suggestion of a system or method such as that described and claimed herein.
In order to overcome the disadvantage of existing solutions, it would be advantageous to have a system and method of determining when a radio telecommunications network should switch between one grade of service and another based upon a highly accurate and reliable estimate of the BER. The present invention provides such a system and method.